With the rapid development of social economy, transactions between merchants and customers are increasingly frequent. Self-service terminals (such as ATM, i.e., automatic teller machine) are greatly favored by customers due to advantages such as being convenient and efficient, 24 hours self service, wide distribution, and etc.
In a conventional self-service terminal, for example an ATM, an irregular-shaped mouth is mounted on a port of a card reader to protect a bank card, prevent the bank card from dropping and prevent the bank card from being taken away by criminals. However, there is also a potential safety hazard. While a customer is operating at an interface to perform a transaction after inserting a bank card into the card reader and entering a password, if a lawbreaker, at this time, inserts a false card into the irregular-shaped mouth of the card reader and then tells the customer that the customer's bank card has exited, and the customer, upon seeing the false card in the irregular-shaped mouth of the card reader, would consider that his own bank card has exited, and then takes out the false card in the irregular-shaped mouth of the card reader and leaves. Actually, the bank card of the customer is still in the card reader and the correct password has been entered; at this time, the lawbreaker may perform a transaction and withdraw cash from the bank account of the customer. This is how the lawbreaker stealthily substitutes a false card for the bank card of the customer and steals cash from the bank account of the customer at present by utilizing the feature of the conventional card reader that a card can be inserted into the irregular-shaped mouth of the card reader.
Therefore, in the field of self-service terminals such as ATMs, it is required to provide a method for protecting a card of a customer and effectively preventing the card of the customer from being stealthily substituted, thereby improving the service quality of a self-service terminal and maintaining the trade credit of a merchant.